The present invention relates generally to surgery, and in particular to the use of a carpal tunnel tome to perform carpal tunnel release surgery.
Surgical decompression of the carpal tunnel, which is often referred to as carpal tunnel release surgery, is the most commonly performed surgical procedure in the United States. The condition is frequent in middle-aged persons whose job requires exposure to vibrating tools or chronic, repetitious use of the hands, such as on keyboards or on assembly lines. Carpel tunnel syndrome is normally characterized by some combination of wrist pain, forearm aching, and/or pain, tingling and numbness in the thumb, index and middle fingers. The pain results from compression of the median nerve in an anatomic passageway in the wrist and palm that is frequently referred to as the carpal tunnel.
Historically, the operative procedure designed to eliminate the symptons of carpal tunnel syndrome includes making an incision in the palm--sometimes extending across the wrist--to divide the deep transverse carpel ligament and its proximal fascial extension, and release the pressure on the median nerve. Although the procedure has been highly successful in relieving most patients' symptons, it is often complicated by tenderness around the incision site in the proximal palm and across the wrist. In addition, patients frequently experience "pillar pain" at the base of the thenar and hypothenar eminences, just distal to the wrist crease and on each side of the surgical scar. This post-surgical discomfort has been implicated as the cause for the slow return of patients to occupational activities following conventional carpal tunnel release surgery.
In recent years, there have been efforts made to alter the technique of carpal tunnel release surgery in an effort to minimize the amount of proximal palm and pillar pain, and allow patients to resume normal occupational and domestic activities more quickly. One such method involves making a relatively shorter incision located entirely in the palm and then dividing the deep transverse carpal ligament by straddling the ligament with small blunt scissors which are passed proximately toward the patient's wrist. Although this technique is effective, there is some danger of inadvertent injury to the median nerve or other structures from the tip of the scissors as they are blindly passed in a proximal direction. Further, the length of incision required in order to divide the majority of the ligament prior to scissor passage, may still be large enough to lead to some palmar pain.
The use of one of several endoscopic methods for division of the deep transverse carpal ligament has also received considerable popularity during the past several years. These techniques employ the passage of a special instrument beneath the carpal ligament, such as for example, the method shown in U.S. Pat. No. 5,029,573 to Chow, and then utilize fiberoptics and special cutting instruments to observe and divide the ligament. Although efforts have been made to make these techniques as simple and safe as possible, they still require specialized training and a reasonably long learning curve before the surgeon becomes adept at their use. Complications such as injury to or division of, the median nerve, one of its branches, the tendons within the carpal vault or the superficial arterial arch of the palm have been described with disconcerting frequency. In some reported cases, the instrument has actually been passed into the wrong passageway where injury may occur to the ulnar nerve or artery. Endoscopic carpal tunnel release surgery averages from 30 to 60 minutes for completion and can be done under either a general or local anesthesia. Apart from being a rather lengthy procedure, endoscopic techniques have been challenged as not always being consistent in their ability to completely divide the transverse carpal ligament.
What is needed is a simple, safe and effective technique for division of the deep transverse carpal ligament that requires only a small mid-palmar incision and utilizes a small cutting instrument designed to protect adjacent tissues when cutting the ligament.